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 A010878 a(n) = n mod 9. 30
 0, 1, 2, 3, 4, 5, 6, 7, 8, 0, 1, 2, 3, 4, 5, 6, 7, 8, 0, 1, 2, 3, 4, 5, 6, 7, 8, 0, 1, 2, 3, 4, 5, 6, 7, 8, 0, 1, 2, 3, 4, 5, 6, 7, 8, 0, 1, 2, 3, 4, 5, 6, 7, 8, 0, 1, 2, 3, 4, 5, 6, 7, 8, 0, 1, 2, 3, 4, 5, 6, 7, 8, 0, 1, 2, 3, 4, 5, 6, 7, 8, 0, 1, 2, 3, 4, 5, 6, 7, 8, 0, 1, 2, 3, 4, 5, 6, 7, 8, 0, 1, 2, 3, 4, 5 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS Periodic with period of length 9. The digital root of n (A010888) is a very similar sequence. The rightmost digit in the base-9 representation of n. Also, the equivalent value of the two rightmost digits in the base-3 representation of n. - Hieronymus Fischer, Jun 11 2007 LINKS Ely Golden, Table of n, a(n) for n = 0..10000 Index entries for linear recurrences with constant coefficients, signature (0,0,0,0,0,0,0,0,1). FORMULA Complex representation: a(n)=(1/9)*(1-r^n)*sum{1<=k<9, k*product{1<=m<9,m<>k, (1-r^(n-m))}} where r=exp(2*pi/9*i) and i=sqrt(-1). Trigonometric representation: a(n)=(256/9)^2*(sin(n*pi/9))^2*sum{1<=k<9, k*product{1<=m<9,m<>k, (sin((n-m)*pi/9))^2}}. G.f.: g(x)=(sum{1<=k<9, k*x^k})/(1-x^9). Also: g(x)=x(8x^9-9x^8+1)/((1-x^9)(1-x)^2). - Hieronymus Fischer, May 31 2007 a(n) = n mod 3 + 3*(floor(n/3)mod 3) = A010872(n) + 3*A010872(A002264(n)). - Hieronymus Fischer, Jun 11 2007 a(n) = floor(12345678/999999999*10^(n+1)) mod 10. - Hieronymus Fischer, Jan 03 2013 a(n) = floor(1513361/96855122*9^(n+1)) mod 9. - Hieronymus Fischer, Jan 04 2013 MAPLE A010878 := proc(n)     modp(n, 9) ; end proc: seq(A010878(n), n=0..100) ; # R. J. Mathar, Sep 09 2015 MATHEMATICA Array[Mod[#, 9]&, 105, 0] (* Jean-François Alcover, Jan 30 2018 *) PadRight[{}, 120, Range[0, 8]] (* Harvey P. Dale, Dec 19 2018 *) PROG (Haskell) a010878 = (`mod` 9) a010878_list = cycle [0..8]  -- Reinhard Zumkeller, Jan 09 2013 (PARI) a(n)=n%9 \\ Charles R Greathouse IV, Sep 24 2015 CROSSREFS Partial sums: A130487. Other related sequences A130481, A130482, A130483, A130484, A130485, A130486. Sequence in context: A207505 A235049 A031087 * A257849 A190727 A195832 Adjacent sequences:  A010875 A010876 A010877 * A010879 A010880 A010881 KEYWORD nonn,easy AUTHOR STATUS approved

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Last modified January 19 15:53 EST 2019. Contains 319307 sequences. (Running on oeis4.)